When problems occur in software for a television receiver, it is necessary to update the software in order to correct the problems. For this reason, a software updating circuit is suggested for updating software for a television receiver. For example, a software updating circuit described in JP 10-164446 A is provided with a changeover switch that enables software to be changed in a market adjustment mode via a variety of input/output terminals in a television receiver.
FIG. 7 is a block diagram showing a conventional software updating circuit. The software updating circuit in FIG. 7 comprises a flash ROM (Read Only Memory) incorporating microprocessor 101, a switching circuit 103, and a signal processor 104.
Software 109 is written in the flash ROM in the microprocessor 101. The microprocessor 101 outputs a clock/data line switching signal 102 to the switching circuit 103. The switching circuit 103 feeds a clock/date signal 108 for updating the software to the microprocessor 101.
The television receiver has an S video input terminal 105. The S video input terminal 105 includes a luminance signal input terminal 106 and a chrominance signal input terminal 107. The S video input terminal 105 is connected with a board or a personal computer 110 for updating the software.
In the example of FIG. 7, when the television receiver enters a market adjustment mode, update software is input from the software updating board or the personal computer 110 by way of the luminance signal input terminal 106, the chrominance signal input terminal 107, and the switching circuit 103 to the microprocessor 101 as the clock/data signal 108.
In this manner, the software 109 for the microprocessor 101 is updated by the clock/data signal 108 from the software updating board or the personal computer 110.
With the conventional software updating circuit, however, a service man has to visit a house to set the television receiver in a market adjustment mode before connecting a special software updating board or the personal computer 110 to the S video input terminal 105 of the television receiver.
Further, even if such conditions for software updating are satisfied, the operation of software updating is so complicated that a user cannot update software on his or her own at home without a service man visiting his or her house.